Dear Concerned., Thanks for writing to us. In all probabality if the x-ray has not indicated any bony involvement., no hairline fracture also,then there could be a possibility of Soft tissue injury for ligaments/cartillages/muscle tendinous attachments which are naturally radioluscent and invisible in a Plain X-Ray of knee joit. For pin pointing the diagnosis, specialised investigations such as MRI of knee joint and ankle are required to be done. Immobilisation;-The injured portion of the body needs to be given adequate rest so that the approximation of the strucures lead to proper healing of soft tissue. kindly use appropriately sized Crepe Bandage/Tubigrip. Analgesia;As the pain is severe ,pls take opioid analgesics such as Tramadol dosage and brands as decided by your MD. In addition the Gastrointestinal Side effects can be reduced by H2 Receptor antagonists such as Ranitidine. The unaffected joints in the lower limb have to be adequately moved to prevent freezing of joints. In the mean time on getting MRI reports and pinpoiting of diagnosis say for Example., Meniscal Tear, consult an Ortho Surgeon to institute minimally invasive arthroscopic/endoscopic surgery. wishing you a speedy recovery., Best Regards., Dr Lt Cdr ASN Bhushan., Ex-Navy